There's something about Mary Benji! It's been quite a while since actress Cameron Diaz has been in a high-profile relationship, but rumor has it that she is now dating Good Charlotte guitarist Benji Madden.

Cameron, 41, hasn't been in a serious relationship since splitting up with baseball star Alex Rodriguez in September 2011. Now, sources are reporting that she has been dating Benji, 35, for the past several weeks.

"They've spent a lot of time at Cameron's house," an insider tells People. "Cameron seems very happy with Benji. He is the nicest guy and treats her like a lady." They were spotted on May 16 working out at a Equinox gym together in Los Angeles.

"They seemed very friendly," an onlooker at the gym says. "And they looked like they were trying to avoid [being seen outside], but Cameron was super friendly with other people [at the gym]. She even taught a girl how to use one of the arm weight machines." Aww!

Us Weekly reports that it was actually Benji's sister-in-law, Nicole Richie, who introduced the new couple. Nicole — who got married to Benji's twin, Joel Madden, in 2010 — is good friends with the Other Woman actress and apparently had a hunch that she would get along with Benji.

Cameron has previously dated such hotties as Jared Leto and Justin Timberlake, while Benji has been linked to Paris Hilton and was rumored to have hooked up with Miley Cyrus recently. We wish the best to Cameron and Benji!